Smad3 is a key mediator of the canonical TGF-β signaling pathway and plays an important role in TGF-β1-mediated transcriptional regulation. However, the function of Smad3 in crustaceans such as shrimp, is still poorly understood and needs to be further explored. We characterized Litopenaeus vannamei Smad3 (LvSmad3) and its biological functions were investigated in response low temperature stress. Full-length LvSmad3 cDNA was 2341bp and contained an open reading frame (ORF) of 1326 bp that encoded a 441 amino acid long protein, with a predicted molecular mass of 48.35 kDa. Phylogenetic analysis revealed that LvSmad3 has a high degree of similarity with other known species. LvSmad3 mRNA was detected in all the tested tissues and highest transcription occurred mostly in gills. Further research showed that suppressing the expression of Smad3 could reduce ROS production, DNA damage and the apoptosis rate in shrimp hemocyte under low temperature compared with the dsGFP group. Thus, we speculated that Smad3 could promote the apoptosis of hemocytes. We confirmed that Smad3 could inhibit apoptosis in the hepatopancreas by suppressing the expression of pro-apoptotic genes. Taken together, the silencing of Smad3 can reduce ROS production induced by low temperature stress, weaken the damage to hemocytes and the hepatopancreas by inhibit the apoptosis.

Smad3 是经典 TGF-β 信号通路的关键介质，在 TGF-β1 介导的转录调控中起重要作用。然而，Smad3在虾等甲壳类动物中的功能仍然知之甚少，需要进一步探索。我们表征了南美白对虾研究了 Smad3 (LvSmad3) 及其生物学功能以应对低温胁迫。LvSmad3 cDNA全长2341bp，开放阅读框（ORF）为1326bp，编码441个氨基酸长的蛋白质，预测分子量为48.35 kDa。系统发育分析表明LvSmad3与其他已知物种具有高度相似性。LvSmad3 mRNA在所有受试组织中均检测到，最高转录主要发生在鳃中。进一步研究表明，与 dsGFP 组相比，抑制 Smad3 的表达可以降低低温下虾血细胞中 ROS 的产生、DNA 损伤和凋亡率。因此，我们推测Smad3可以促进血细胞的凋亡。我们证实 Smad3 可以通过抑制促凋亡基因的表达来抑制肝胰腺中的细胞凋亡。综上所述，Smad3的沉默可以减少低温应激诱导的ROS产生，通过抑制细胞凋亡来减弱对血细胞和肝胰腺的损伤。